8O 



H. E. EWING. 



Individual 

 1 1625 

 II26 



II62? 

 1 1 628 

 1 1629 

 II62IO 



II63I 

 II632 

 H633 

 I 1634 



11536 



II639 



II63IO 



II63II 



II63I2 



II63I3 



TABLE VII. (continued). 



Length in Millimeters j 



I-5I 



1.54 



I-S7 

 1.63 

 1-29 

 I.SI 



1.76 

 1. 80 

 1-54 

 1-74 



1-49 

 1.71 

 1.56 

 1.70 



1.57 

 1.43 

 I.4I 

 I.7I 



Fraternal Mean. 



I-527 



I.6I7 



Second Score of Generations; Temperature so Regulated that only 

 Wingless forms Produced, a Six-day Interval Being Allowed 

 for Growth and Reproduction of Each Generation. 



For the second score of generations it was decided to make the 

 conditions of the experiment more definite. Having learned the 

 effect of temperature on the size of the individuals, it was de- 

 cided to place them in a room where the temperature was less 

 variable. This was done and temperature records were taken 

 daily. During the whole of this part of the experiment no such 

 variations in temperature were allowed as those which affected 

 the first score of generations. By means of experiments else- 

 where reported, I learned that under suboptimum growth con- 

 ditions the winged forms would not appear. The optimum 

 temperature for the wingless forms was found to be about 65 F. 

 So well was the temperature controlled for the second twenty 

 generations that not a single winged form appeared during the 

 entire subexperiment. It was further decided that the same 

 period of time should be allowed for growth and reproduction 

 in each generation. The period allowed was 6 days. 



